#include "cs.h"
/* remove duplicate entries from A */
int cs_dupl (cs *A)
{
    int i, j, p, q, nz = 0, n, m, *Ap, *Ai, *w ;
    double *Ax ;
    if (!CS_CSC (A)) return (0) ;		/* check inputs */
    m = A->m ; n = A->n ; Ap = A->p ; Ai = A->i ; Ax = A->x ;
    w = cs_malloc (m, sizeof (int)) ;		/* get workspace */
    if (!w) return (0) ;			/* out of memory */
    for (i = 0 ; i < m ; i++) w [i] = -1 ;	/* row i not yet seen */
    for (j = 0 ; j < n ; j++)
    {
	q = nz ;				/* column j will start at q */
	for (p = Ap [j] ; p < Ap [j+1] ; p++)
	{
	    i = Ai [p] ;			/* A(i,j) is nonzero */
	    if (w [i] >= q)
	    {
		Ax [w [i]] += Ax [p] ;		/* A(i,j) is a duplicate */
	    }
	    else
	    {
		w [i] = nz ;			/* record where row i occurs */
		Ai [nz] = i ;			/* keep A(i,j) */
		Ax [nz++] = Ax [p] ;
	    }
	}
	Ap [j] = q ;				/* record start of column j */
    }
    Ap [n] = nz ;				/* finalize A */
    cs_free (w) ;				/* free workspace */
    return (cs_sprealloc (A, 0)) ;		/* remove extra space from A */
}
